This invention relates to a propeller shaft fitting structure for a marine propulsion unit, and more particularly to an improved arrangement for mounting a propeller shaft within the lower unit of a marine propulsion unit.
Many forms of marine propulsion units employ forward/neutral/reverse transmission within their lower end. These transmissions include a pair of counter-rotating bevel gears which are driven by a driveshaft and which are journaled on a propeller shaft. The propeller shaft is, in turn, journaled within the lower unit housing in one of a wide variety of manners and these driven bevel gears are adapted to be selectively coupled to the propeller shaft for driving the propeller shaft in the selected forward and reverse directions.
In one commonly used type of supporting arrangement, the forwardmost driven bevel gear is mounted within the lower unit housing on a fixed bearing before the propeller shaft is inserted. The propeller shaft is, in turn, journaled within a bearing carrier and a subassembly consisting of the bearing carrier and propeller shaft are then inserted into the lower unit housing through an opening in its rear face for final assembly. However, it is normally the practice to journal the propeller shaft only at the rear end of the bearing carrier. As a result, upon installation, the bearing carrier must be aligned with the complementary opening of the lower unit housing and the forward end of the propeller shaft must be slipped into the hub of the forwardmost driven bevel gear. Since the forward portion of the propeller shaft is, however, generally unsupported by the bearing carrier, then it is difficult to accurately align the components.
It is, therefore, a principal object of this invention to provide an improved arrangement for fitting the propeller shaft into the lower unit of a marine propulsion unit.
It is a further object of this invention to provide an arrangement between the bearing carrier and propeller shaft so that the forward end of the propeller shaft will be located so as to facilitate insertion, but wherein this forward location need not provide a bearing support for the propeller shaft.